The present invention relates to the general field of tuning clearance at rotor blade tips in a gas turbine. More specifically, the invention provides a tuning device for a high-pressure turbine of a turbomachine, which device is equipped with means for balancing air flows.
A gas turbine, such as a high-pressure turbine of a turbomachine, includes a plurality of rotor blades that are disposed in the passage for the hot gas that comes from a combustion chamber. Around the entire circumference of the turbine, the rotor blades of the turbine are encompassed by an annular stator. Said stator defines one of the walls for the stream of hot gas flowing through the turbine.
In order to increase the efficiency of the turbine, it is known to minimize the clearance between the turbine rotor blade tips and the facing portions of the stator.
In order to do so, clearance tuning means have been designed for tuning clearance at the blade tips. Generally, said means come in the form of annular pipes which surround the stator and which convey air that is drawn from other portions of the turbomachine. Depending on the operating speed of the turbine, the air is injected onto the outer surface of the stator in order to modify its temperature, thereby causing thermal expansion or contraction capable of varying the diameter of said stator.
Existing tuning devices do not always enable highly uniform temperature to be obtained around the entire circumference of the stator. A lack of temperature uniformity generates distortions in the stator which are particularly detrimental to the efficiency and the lifetime of the gas turbine.